Tag Archives: Space Exploration

When someone brings up the idea that life as we know it originated from space, it is easy to think they are crazy. However, instead of thinking of lanky-green aliens, would this idea seem so far fetched if they were talking about micro-organisms? There is a hypothesis called panspermia which hypothesizes that life originated elsewhere in space and migrated to Earth. This alien life would have arrived from another planet on a meteorite.

Comet Hale-Bopp courtesy kevindooley Flickr

There are three important stages a micro-organism would have to survive for a succussful journey. Must first survive take off, then space travel and finally survive the impact upon landing. There have been studies to evaluate the likelihood of surviving any of these phases.
Gerda Horneck from the German Aerospace Center stated in a paper which evaluated spore survival during space travel that, “There are certain areas at the rim of the impact crater, called the spallation zone, where by reflection of the shock wave the temperatures do not exceed 100 degrees Celsius.” This means that it’s cool enough for some spores to survive ejection from a planet.Rocco Mancinelli of the SETI Institute with his colleagues have published a review on bacteria surviving space journey. Their study supports that microbes could survive a trip through space. Micro-organisms hitching a ride on a meteorite can get protection from the dangerous UV radiation if they are below the surface.
A study published in 2001 explored the likelihood of bacterial spores surviving the landing impact. This study found that spores could survive impact scenarios that are similar to those that meteorites experience.

Micro-organism arriving from Mars seems the most likely since it is a relatively short journey. First it must be proven that there is or was life on Mars, a group of researchers from MIT are hoping to test Mars’ surface for microbes. If microbes are found, the next step would be to do DNA/RNA sequencing on them. With these tests we may be able to prove that our neighbouring planet may actually be our mother planet.

There is no definite answer to how life as we know it began on Earth. I found this research interesting because I never heard of this idea before. After looking at the papers concerning bacteria surviving space travel, I don’t think this idea is far fetched. I think it is a rather simple explanation to how Earth became inhabited. If Martian microbes could be sequenced and a connection was found between them and any organisms genome here on Earth, that would be incredible. I think it would be hard for many people to accept this idea because it makes our origins even more mysterious.

Humanity has just reached another milestone in space exploration. Yesterday, on March 17, NASA’s MESSENGER probe entered orbit around Mercury becoming the first spacecraft to ever do so.

MESSENGER probe approaching orbit around Mercury

MESSENGER (actually short for Mercury Surface, Space Environment, Geochemistry and Ranging) was launched almost 7 years ago in August of 2004. It was designed to examine the magnetic field around mercury, as well as chemical composition and geology of the surface.

Since then, MESSENGER has made three flybys past Mercury and has made some interesting discoveries that have puzzled scientists for years.

Evidence of Volcanic activity on the surface of Mercury

Back in July of 2008, MESSENGER made the startling discovery of water present in Mercury’s exosphere (the uppermost later of the atmosphere). It also found evidence of extensive volcanic activity on Mercury’s surface. Previously, scientists believed that the volcanic gases would have long ago exited Mercury or had been absent at its formation.

MESSENGER’s new mission will have it begin to throughly examine the surface for the chemical signatures of these gases with an array of seven instruments (set to be activated on March 24). The probe will also study the presence of water on Mercury and also examine the planet’s core.

MESSENGER's gravity assist maneuvers

What made MESSENGER’s voyage to Mercury interesting were some of the challenges that scientists had to overcome. Normally, a probe approaching the planet would become too accelerated due to the force of the Sun’s gravity and fly past the planet before it could maintain orbit. MESSENGER had to overcome this by using a series of gravity assist maneuvers to slow it down. These maneuvers utilize the gravity of a planet to change the path of the spacecraft. If you’ve ever seen the movie “Armageddon”, this was like the scene where the spaceship did the “roadrunner thrust move” around the Moon. MESSENGER had to utilize the gravity from Mercury, Venus and Earth to perfect its trajectory to orbit the planet.

What’s truly remarkable is that these series of gravity assisted moves mean that MESSENGER has traveled 7.9 billion kilometers through space since 2004.

The other challenge for scientists was thermal damage due to Mercury’s high surface temperatures. They solved this by making MESSENGER have a highly elliptical orbit around the planet. The trajectory takes the probe within 200 km of the surface then 15,000 km away, presumably when the temperatures are hottest. One of these cycles takes 12 hours.

The probe’s first set of measurements are scheduled to be sent to Earth on April 4. Who knows what’s waiting to be discovered beneath the surface of Mercury!